1. Field of the Invention
The present invention relates to a recording apparatus that performs recording by using a recording head for discharging ink, and a recording position adjustment method for the recording apparatus.
2. Description of the Related Art
In ink jet recording apparatuses, conventional methods for correcting deviation of an impact position or a dot-recorded position (ink droplet) on a recording medium are known. Japanese Patent Application Laid-Open No. 11-240146 discusses a technology that can accurately correct a recording position irrespective of the position in a scanning direction even when a distance between a carriage, having a recording head loaded thereon, and a recording medium changes in the scanning direction, by controlling ink discharge timing according to a scanning-direction position of the carriage.
When the ink discharge timing is controlled according to the scanning-direction position of the carriage, a dot can be recorded in a target recording position. However, a white streak or a black streak may be generated in the position of correcting the discharge timing.
FIGS. 20A to 20C illustrate generation of streaks when the ink discharge timing is controlled according to the scanning-direction position of the carriage by a conventional recording position adjustment method. FIG. 20A schematically illustrates a relationship between the scanning-direction position of the carriage and a recording position deviation amount. The vertical axis indicates a deviation amount with respect to a broken-line target recording position 42. As illustrated in FIG. 20A, the deviation amount of the recording position in the scanning direction continuously changes.
FIG. 20B illustrates, if the recording position deviation changes in the scanning direction as illustrated in FIG. 20A, a relationship between a recording position deviation amount and a discharge timing shift amount when the ink discharge timing shift amount is generated according to the recording position deviation amount. The discharge timing shift amount can be generated in units of one step of a carriage encoder. In FIG. 20B, the ink discharge timing is corrected to be earlier or later by one step than the current discharge timing.
When the discharge timing is corrected as described above, discontinuity occurs in shift amount of the recording position. FIG. 20C illustrates arrangements of dots 100 in the scanning direction when no recording position adjustment is performed in a plurality of positions in the scanning direction (C-1) and when recording position adjustment is performed (C-2). FIG. 20C illustrates target recording positions with broken lines 15, and recording positions are corrected at predetermined intervals in the scanning direction. When no recording position adjustment is performed in a plurality of positions in the scanning direction, the recording position deviation is corrected for a given target recording position 15 (left side in FIG. 20C), and a deviation amount between dots is very small in an adjacent area. However, the recording position deviation occurs in the case of the target recording position 15 at the right side in FIG. 20C.
On the other hand, when recording position adjustment is performed in a plurality of positions in the scanning direction, the recording position deviation is corrected for a plurality of target recording positions in the scanning direction. When such recording position adjustment is performed, dots can be recorded in positions close to the target recording positions in all recording positions. However, in a position (target recording position) where a shift amount changes, a change amount larger than a minute deviation amount from an adjacent dot is added, thus generating a streak in an image. In the illustrated example, a white streak 14 is generated, and black streaks may be generated depending on overlapping of dots.